Seal and method for making the same



Patented Mar. 9, 1926.

f-UNITEDSTATES PATENT OFFICE.

DANIEL SNYDER GUSTIN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTINO HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

SEAL AND METHOD FOR MAKING THE SAME. 7

A10 Drawing.

To all whom it may concern:

Be it known that I, DANIEL SNYDER Gus- TIN, a citizen of the United States, and a resident of East Orange, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Seals and Methods for Making the Same, of which the following is a speclfication.

My inventionrelates to the construction of joints or unions between a silicious material and metals, and more particularly it relates to leading-in conductors which are to be sealed in a container of glass or other vitreous material through which the conductor extends and with which said conductor must form a gas-tight seal.

An object of my invention is to provide a-method of uniting a metal or alloy to a silicious material.

Another object of my invention is to provide a novel metallic lead-in wire which will make a satisfactory gas-tight seal with glasses having different coefficients of expansion.

Other objects of the invention will be apparent from the following description.

I have discovered that chromium readily wets with glass, and, for that reason, itmay be employed as a leading-in conductor or as a medium for joining or Welding to glass a conductor which does not have t e property of wetting with glass.- In utilizing this property of chromium, many applications of it may be made in joining or sealing-in leading-in conductors to vessels or containers in which gas-tight joints are required for the eflicient operation thereof.

, In practice, a gas-tight seal may be obtained by coating with chromium a metallic core which, in itself, may be composite in structure and have a predetermined coefficient of expansion approximating that of the glass into which the conductor is to be sealed. By having a relatively thin deposit of the chromium upon the metallic core, the coefiicient of expansion of the core material is substantially unaffected. It is, therefore, apparent, that, to produce a satisfactory seal between a metal and a silicious material, it is only necessary to employ a metal havin a coeflicient of expansion substantially equa to that of the silicious material, and to join this metal, through the agency of chromium,

Application filed March 30, 1921. Serial No. 457,101.

to the wall of the silicious object which mav be glass. i

Heretofore, leading-in conductors have been made of metals which have the charac teristic of wetting with glass and have a coefficient of expansion substantially equal to that of the glass into which they are sealed. The number of metals heretofore known as having these two characteristics is small, and, for this reason, efforts have been made to develop leading-1n conductors of other metals or of metals alloyed together in various proportio'ns.

While platinum, tungsten, and molybdenum have been successfully used for leading-in conductors, the expensiveness of platinum is obviously an objection to its commercial use, and the use of tungsten and molybdenum is confined to hard glasses, inasmuch as they cannot be successfully used with soft glasses.

Among the newly developed conductors, is a composite wire consisting of a metallic core having a coefficient of expansion less than that of the glass into which it is to be sealed and a layer of metal on said core having a coefiicient of expansion greater than said glass. I

My invention, as relating to a leading-in conductor, particularly useful for incandescent electric lamps, is distinguished from the above described composite wire type of leading-in conductor by employing a metal which satisfactorily wets with glass to perform the function of a sealing medium or agent, and applying this metal to' a core which has a coeificient of expansion substantially equal to the glass into which it is to be sealed. The wetting metal, in this instance, is preferably of small volume, and, therefore, its association with the-core does not materially change the coefficient of expansion of the core. NVhen desirable, the metal employed as the medium or agent may be of suflicient volume to act alone as the electrical leading-in conductor.

Leading-in conductors of the type set forth in this application eliminate certainv undesirable features of the so called graded seals; one of these features being excessive assembly of glass necessarily required in that type of seal. My type of leading-in conductor also provides a quick, satisfactory method of attaching various types of electrical conducting metals or alloys to glass or other materials of like composition, and eliminates objectionable features inherent in other types of seals. 1 In the present mode of manufacturing certain types of incandescent lamps, such, for example, as those of the miniature type, a copper-coated conductor has the disadvantagethat the copper is oxidized bv the flame employed in fusing the glass to the conductor, so that trouble is experienced in making a satisfactory gas-tight joint between the conductor and the glass.

My invention, for purposes of description, will be set forth as directed to a composite metal leading-in conductor for use in incandescent electric lamps and further,

it will refer to a conductor comprising a metallic core haringa coeflicient of expansion approximating that of the glass into which it is to be sealed. The core is preferably provided with a thin layer of chromium. One of the purposes of covering the metallic core with chromium is to provide a material which will make a satisfactory joint or union with the glass, and it is to be noted that a coating" of chromium is not specifically applied to alter the coeflicient of expansion of the metal core, as has previously been proposed for other combinations of metals, as there is no requirement to produce a composite leading-in wire of metals which have coeflicientsof expansion difierent from that of the core. Moreover, the thickness of the coating of chromium is not sufiicient to materially change the coefficient of expansion of the core. Any desired core may be employed upon which to apply the layer of chromium, and, if desired, a metal or al- 10y having the proper coeificient-of expansion, or a composite metal core with a predetermined coeflicient, may be employed.

In practicing my invention any material may serve as the core, its selection being directed by the character of seal desired to be made. However, for the purpose of illustration, I will set forth a. process for making .a satisfactory leading-in conductor or.

wire which may be used in the manufacture of incandescent lamps; In this instance, the core material is preferably nickel-iron alloy having a suitable coefficient of expansion, and chromium may be deposited there on by electrolysis. for the deposltion of the chromium is pro ferred as it provides means for more ac.-

curately controlling the thickness and uniformitv of the deposit. In using this method the variable factors, such as the composition and temperature of the electrolyte and the current density mayv be adjusted, by anyone skilled in the art, to secure a satisfactory deposit of the chromium on the nic e -iron c re W at; he de i ed The electrolytic method known processes as sherardizing or caloriz- I ing metals.

This invention is capable of bemg employed for a variety of purposes and under various'clrcumstances and 1t 1s considered that such modifications come within the scope of this invention.

\Vhat is claimed is 1. As a leading-in conductor, a. wire having a chromium surface. I

2. As a leadingin conductora chromium coated wire.

3. As a leading-in conductor, a metallic core having a sheathof chromium.

4. As a leading-in conductor, a composite wire comprising a chromium-coated alloy.

5. As a leading-in conductor a. com osite wire comprising a chromium-coated nlckeliron alloy.

6. A leading-in conductor comprising a wire composed of a metallic core having an electrolytic deposit of chromium thereon.

7. As a leading-in conductor, a Wire having a layer thereon presenting a surface entirely of chromium.

8. As a leading-in conductor, a composite wire comprising an alloy having a layer thereon consisting entirely of chromium.

9. A leading-in conductor for avitreous container, said conductor including a. portion consisting of a metallic core having a coefiicient of expansion substantially the same as the contamer and a layer of chrommin on said core to provide a gas-tight seal between the leading-in conductor and the container.

10. A composite leading-in conductor for a glass container adapted to extend from within said container to the exterior thereof and comprisin a metallic corehaving a layer of chromlum thereon to provide a. gastlght seal with the wall of the oontamer through which, the conductor passes.

11. A leading-in conductor for a. vitreous container including a section consisting of a metallic core having a coeflicient of expansion substantially the same as the vitreous material of the container and a. layer of chromium. on said core to provide a. gastlght seal between the leading-in conductor. and the container.

12. An article of manufacture consisting of a wall of glass having sealed therethrough a chromium coated wire.-

13. The combination of a vitreous maof chromium united gas-tight contact with said material,

14. The combination with an evacuated incandescent electric lampbulb of vitreous material, of a composite leading-in Wire passing through a Wall of the bulb, said leading-in wire having an external layer entirely of chromium for contact, with the material of the Wall of the bulb to provide a gas-tight seal. a

15. The combination of a gas-tight receptacle having a Wall of vitreous material of I a composite leading-in Wire sealed therein,

said Wire comprising a metallic core and coating thereon of chromium.

16. The combination of a vitreous ma terial, a metallic core sealed in said-material,

.DANIEL SNYDER GUSTIN. 

